Inherently dissipative polymers (IDPs) are a class of polyether elastomers which have inherent volume resistivity in the 1×105 to 1×1012 ohm-cm. Examples include polyethylene oxide-based polyether urethanes, polyether amides and polyether esters, and copolymers of ethylene oxide such as ethylene oxide/propylene oxide or ethylene oxide/epichlorohydrin. IDPs are used in alloys with other thermoplastics as a means to impart a level of conductivity sufficient to render the plastics static dissipative (surface and volume resistivities in the 1×105 to 1×1012 range). For example, U.S. Pat. No. 5,574,104 relates to polymer compositions comprising a polyether polyurethane IDP which can be blended with one or more base polymers. The subject blends have useful static dissipative properties and exceptional cleanliness, making them suitable for handling of sensitive electronic components and devices. However, the blends are generally not transparent.
U.S. Pat. No. 6,140,405 relates to a low molecular weight polyether oligomer which is modified with a salt, preferably containing lithium, during a chain extension reaction of the polyether oligomer to form IDP products such as polyurethanes, polyether amide block copolymers and polyether-ester block copolymers. The reaction product polymers exhibit lower surface and volume resistivities and static decay times, relative to other IDPs, yet are free of excessive amounts of extractable anions, particularly chlorine, nitrate, phosphate and sulfate.
U.S. Pat. Nos. 4,332,919, 4,302,558 and 4,384,078 describe inherently dissipative acrylic polymers made by a core/shell process. This class of IDP polymers is transparent, but suffers from high resistivity, slow static decay times and high off-gassing of volatile impurities, making it less desirable for sensitive electronic handling applications.
U.S. Pat. No. 6,225,407 relates to a polymer blend comprising one or more cycloolefin copolymers and one or more types of core-shell particles or one or more copolymers which are composed to some extent of rubbers with low glass transition temperatures, or a combination of one or more types of core-shell particles and of one or more copolymers which are composed to some extent of rubbers with low glass transition temperatures.
U.S. Pat. No. 6,054,533 relates to a compatibilized blend of a thermoplastic elastomer and a polyolefin. The compatibilizer is a thermoplastic polyurethane formed by the reaction of a substantially hydrocarbon intermediate such as a polybutadiene polyol, a diisocyanate such as MDI, and an amine or diol chain extender such as neopentyl glycol. The compatibilizer has high amounts of soft segments therein and imparts improved properties to blends of a thermoplastic elastomer and polyolefin such as good impact resistance, good tensile strength, good tear resistance, and good delamination resistance. These compositions are not transparent.